Apparatus and method for splicing light conductors in a composite cable

ABSTRACT

An apparatus and method for splicing light conductors in composite cables, in particular marine cables, comprising a plurality of spliced cable sections of power conductors and sections of light conductors. With a view to uninterrupted armouring along the entire length and thus the ability to maintain a sufficient tensile and flexural strength, the splice of the light conductors is provided at a distance from the splice of the power conductors and with a cross-sectional contour which essentially corresponds to the cable cross-section. Then the armouring is wound uninterruptedly around the cable and encloses the splices of the power conductors as well as the light conductors.

The invention concerns an apparatus and method for splicing lightconductors in composite cables, in particular marine cables, and of thetype comprising a plurality of power conductors as well as a pluralityof light conductors.

Marine cables frequently have rather large dimensions because of a verystrong armouring. The armouring is necessary because the cables areadapted to be laid on the sea bed, and it will be appreciated that theymay be subjected to very great tensile forces both when being laid andif gripped e.g. by the anchor of a ship.

In a new cable type which, in addition to power conductors, comprises aplurality of light conductors, the cable, like other cables, is splicedat predetermined intervals, and it has been found to be a very difficultjob to make a cable splice with sufficient relief for the lightconductors without increasing the cable diameter considerably.

Based on purely rational considerations, it might be imagined that thepower conductors as well as the light conductors might advantageously bespliced at the same site. This, however, results in an inexpedient cablecross-section in the region of splice, in the form of a large thickeningof the cable, which renders it is possible in practice to effectarmouring at this site by the usual armouring machine.

Secondly, a great thickening makes it very difficult subsequently toroll up the cable on a drum or rotary disc, adapted for the purpose, sothat the cable easily gets tangled, and moreover, rolling-up layer uponlayer may result in some bends and thus tensile and compressive stresseson each side of the splice sleeve.

Thirdly, the thickening may cause problems during laying of the cable inthe form of difficult or impossible passage through the cable payingmachinery of the ship and through possible equipment for ploughing orflushing the cable into the ground.

The GB Patent Application 2 169 093 A discloses a cable assembly which,in addition to pronounced cable components, comprises light conductorsand has sleeves for splicing these. These sleeves are provided such thatat a given splice site these are able to accommodate one or more loopsof optical fibres in the diametrical or transverse direction of thesleeve. Thus, this splicing method requires the existence of a mutualgap between the juxtaposed cables.

It will be appreciated that such a sleeve structure causes aninexpedient increase in the cable cross-section at the splice region inconnection with subsequent armouring of the cable.

The object of the invention is to provide a method of manufacturing acomposite cable which is adapted to be armoured uninterruptedly alongits entire length and thus maintain a sufficient tensile and flexuralstrength, and the object is moreover to provide a splice sleeve adaptedfor the method for use in splicing of light conductors so as to providea composite cable having a compact, substantially cylindrical splicecross-section with a diameter which essentially corresponds to thediameter of the unspliced length of cable.

In the inventive method, the power and light conductor splices areprovided mutually offset so as to even out the cable thickeningpreventing proper continuous armouring. Thus, the cable substantiallymaintains its dimensions and is thereby suitable for being rolled up,laid and optionally ploughed or flushed into the ground, and the cablehas moreover uniform tensile and flexural strengths along its entirelength in spite of the splices.

When a composite cable splice sleeve is constructed in accordance withthis invention, a cable splice is provided where a cylindrical andminimum splice site cross-section is advantageously obtained so that theabove-mentioned armouring, rolling-up and paying-out operations arefacilitated.

According to the invention, the light conductor splices are disposed inthe peripheral cross-sectional area of the composite cable, where alsothe splice sites are provided in so-called sections which are removable.This makes the composite cable easy to handle and to service.

The splice sleeves are preferably provided such that the plurality ofsections, i.e. "covers", to receive the light conductors is adapted tothe plurality of power conductors, thereby advantageously providing aminimal dimension and optimal roundness of the jointing sleeve.

The invention will be described more fully below in a preferredembodiment with reference to the drawing, in which

FIG. 1 is a perspective view of a splice sleeve according to theinvention, in an assembled state,

FIG. 2 is an exploded view of the splice sleeve illustrated in FIG. 1,and

FIG. 3 is a sectional view of the assembled splice sleeve of theinvention illustrated in FIG. 1.

FIG. 1 shows a splice sleeve 1 of the invention, shown here in anassembled form without power and light conductors. It appears that thesplice sleeve substantially consists of a plurality of core members 2adapted to be fixed around a plurality of power conductors, provided ina number of three in the illustrated case. These core members, whenassembled, form the actual frame of the splice sleeve. It appears thatthe core members are provided with cylindrical grooves 14 to receive thepower conductors so that the frame, when fixed to it, is essentiallycompletely, sealingly engaged with the conductors. It also appears thatthe core members 2 are ground with external plane faces and secured toone another by means of bolts 10. The plane faces of the core membersare adapted to receive a corresponding number of so-called sections orcovers 3, which have the shape of cylinder segments, and which, whenassembled on the frame, form, in combination with said frame, a cylinderhaving a diameter which essentially corresponds to the cablecross-section.

FIG. 2 illustrates the splice sleeve 1, shown here in an exploded view,and illustrating the internal shape of the sections 3. The plane face ofthe sections or covers 3 has a plane milled-down (recess) 4 which leavestwo cylinder faces 5 co-planar with the edges of the sections. It willbe seen that each of these cylinder faces is formed with a pair oftransverse holes for clamping to the associated core member 2. Since thecylinder faces are flush with the edges of the sections, as mentioned,it will be appreciated that, when clamped to the core members, thesections obtain a sufficient face-to-face engagement for the clampingeffected via bolts 11. It will be seen that the sections at each end areformed with a bore to receive a light conductor from both ends. Each ofthese bores opens into said cylinder faces 5, the actual mouth merginginto a milled groove 8 which is to receive the light conductors whenthese have been passed through the bores 7.

With respect to splicing of the light conductors, it will thus beappreciated that the light conductors, after having been pulled throughthe mentioned bores in each side, undergo a splicing operation of anotherwise known type, following which the resulting, excess lightconductor material is to be placed in the above-mentioned, planemilled-down portion 4. This is performed by placing the actual splice ofthe light conductor in a splice bearing 9 adapted for the purpose, e.g.in the form of additional milling in the milled-down portion 4. Sincethis light conductor splice will preferably be positioned centrally onthe said excess light conductor length, the resulting two lightconductor halves will have to be positioned in the cavity provided viathe milling operation, in a convenient manner. This is done by utilizingthe plane cylinder faces 5 as winding coils so that the light conductorlengths will be in an essentially firmly fixed state when the sectionsor covers 3 are clamped.

FIG. 3 illustrates a cross-section of the above-mentioned splice sleeve1 which is shown here, like in FIG. 1, in an assembled state andlikewise without power and light conductors for the sake of simplicity.It appears how the splice means, in the form of recessed bolts 10 and11, have been rationally positioned so as to provide a cable jointingsleeve comprising a plurality of sections for the light conductorsplices and having a cross-sectional contour and size which essentiallycorrespond to the cross-section of the rest of the cable.

It will likewise be appreciated that when a splice sleeve of this typeis provided where it is possible to armour around the sleeve, astructure is obtained, causing a significant relief of the lightconductors, which would otherwise not be the case if the conditions forthe mentioned armouring process were not present.

I claim:
 1. A method of securing a light conductor splice with respectto a composite cable including light conductors and power conductors,the method comprising assembling power conductors in a bundle, disposinga sleeve around the bundle in a direction along the length of the cable,disposing an end from each of two lengths of a light conductor within arecess in a face of a cable section while the section is apart from thesleeve, splicing the two ends together, retaining the resulting splicewithin the recess, disposing the face of the section against the sleeve,and securing the section to the sleeve.
 2. A method according to claim 1including forming a plurality of splice containing sections, anddisposing the sections around the periphery of the sleeve to form acable of circular cross-section.
 3. A splice sleeve for use in thesplicing of light conductor sections in a composite cable including bothlight conductors and power cables, the sleeve comprising core members(2) forming an encircling housing in which power conductors arecontained, and a plurality of removable sections (3) evenly distributedaround the core members and adapted to contain light conductor splices,external surfaces of the sections (3) together with external surfaces ofthe core members (2) disposed between adjacent sections defining asubstantially cylindrical surface.
 4. A splice sleeve according to claim3 for use with a composite cable including a preselected number of powerconductors, and wherein the number of said removable sections is equalto said preselected number.